1. Field of the Invention
The present invention relates to a method of shaping a metal strip in a hot rolling installation including arranged one after another in a strip displacement direction finishing train, cooling section, and coiler, and to an installation for effecting the method.
2. Description of the Prior Art
It is well known to roll a metal strip, after casting, in a hot rolling installation to reduce the strip thickness to a certain thickness before a further reduction of the strip thickness to a final dimension in a cold rolling installation. The metal strip fed to the cold rolling installation should meet very high requirements with respect to its mechanical and geometrical characteristics, in particular, with regard to its surface evenness.
Simultaneously, there exists a tendency to impart the desired characteristics of a metal strip, which is obtained as a result of following one another, hot and cold rolling, already during the hot rolling, or to provide a hot rolled strip having optimal pre-conditions for the subsequent cold rolling process. Anyway, the boundary condition of the strip is more difficult to achieve during the hot rolling. It is desirable to adapt thinner and wider products to end products as much as possible, and such an adaptation requires a significant thickness reduction during the hot rolling which, in turn, requires application of larger rolling forces in the last rolling mill stands of the hot rolling train. However, application of large rolling forces in the last rolling mill stands of the hot rolling train adversely affects the flatness of the hot rolled strip and, thus, the quality of the strip in its cold condition.
The strip leaves the finishing train at least partially with a non-uniform flatness and/or stress distribution over the strip width. Further, the flatness and/or strip structure changes in the cooling section. The non-uniform characteristics of the hot rolled strip over the strip width lead, directly or indirectly, to different flatness characteristics of the cold strip.
Accordingly an object of the present invention is to provide a method of and an installation for shaping a metal strip which would insure obtaining a uniform flatness and stress distribution already in a hot rolled strip so that a flattened strip is obtained in the cold condition.
A further object of the present invention is to provide a method of and an installation for shaping a metal strip which would insure improved mechanical characteristics and surface structure of the hot rolled strip.